1. Field of the Invention
The present invention relates to a power unit for a small type vehicle including an engine having a valve-operating device provided additionally with a valve operation mode change mechanisms capable of changing the operational modes of engine valves. A crankshaft is provided having an axis set along the vehicle width direction wherein the crankshaft is rotatably mounted on a crankcase of the engine. A speed change mechanism is provided in the course of a power transmission path for transmitting rotational power of the crankshaft to a drive wheel with the speed change mechanism being contained in the crankcase. A clutch device is provided for switching the making/breaking of power transmission between the crankshaft and the speed change mechanism, the clutch device is disposed on a lateral side of the crankcase on the side of one end of the crankshaft. A valve operation controller is provided for controlling the operations of the valve operation mode change mechanisms. A speed change controller is provided for controlling a speed change operation of the speed change mechanism with the valve operation controller and the speed change controller being attached to an engine body inclusive of the crankcase.
2. Description of Background Art
Japanese Patent Laid-Open No. 2003-232236 discloses a vehicle including a speed change controller for controlling the operation of an automatic transmission, and a valve operation controller for controlling the operation timings of engine valves.
In a power unit which has an engine with the axis of a crankshaft set along the vehicle width direction and which is mounted on a small type vehicle such as a motorcycle, a clutch device serving as a heavyweight body is disposed on a lateral side of a crankcase on the side of one end along the axial direction of the crankshaft. Thus, the layout of a valve operation controller and a speed change controller must be optimized so as to prevent the center of gravity of the power unit from being deviated to one side.